CNRP has boycotted parliament since the July election, alleging that Hun Sen was returned to power because of widespread vote-rigging.

It has won the support of some 350,000 garment workers from nearly 500 factories across Cambodia, by promising to nearly double the monthly minimum wage to $160 if it wins a re-run of the July election, which Hun Sen is refusing to hold.

The government is refusing to raise the wage beyond $100 dollars a month and has ordered factories to reopen to prevent damage and job losses in an industry worth $5 billion a year.

Amnesty International and Cambodian rights group LICADHO are demanding an investigation into the violence.